I think I can answer my own question now. It appears to be the time (in seconds) that the BMS is active after charging or discharging ends. Probably a power saving feature. During this time, the BT interface (and probably the PC interface) is inactive as well. The BMS seems to automatically...
I was looking for a 10AH battery, bought 5 MarCum Brute battery's, one reached 10ah, three reached 8ah, and one only reached 6ah. Next I bought a Goldenmate 10ah unit and it tested fine. I'm about to try their 100ah battery.
My 4S 100amp BMS uses 10 ma. while awake and about 1 ma. asleep. 95% of this current flows in the sense leads so they must have a degree of isolation from the B- lead.